Discussion only open while a study is active; v2.11.1

- Community posts, replies, likes and lesson comments are refused (403) for finished and planned studies
- Reading a closed study's community/comments returns an empty list with closed:true
- Discussion hub lists only active studies; community page shows a closed notice
- Lesson page hides Lesson Discussion, 'Discuss this lesson' and 'Go to Community' for inactive studies; Community buttons hidden on study/dashboard pages
- Tests for isStudyDiscussionOpen

Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>

test/study-completion.test.js

@@ -59,3 +59,22 @@ test('re-engagement emails skip students whose only study is finished', async ()
   await scheduleReengagementEmails(async (email) => { sent.push(email) })
   assert.deepEqual(sent, ['c@d.co'])
 })
+
+test('discussion is open only for active studies', async () => {
+  const { isStudyDiscussionOpen } = await import('../server/study-helpers.js')
+  const past = '2020-01-01T00:00:00Z'
+  const future = '2099-01-01T00:00:00Z'
+  state.cachedSiteContent = {
+    studies: [
+      { slug: 'live', status: 'active', sections: [{ id: 'a', releasedAt: past }, { id: 'b', releasedAt: future }] },
+      { slug: 'done', status: 'complete', sections: [{ id: 'a', releasedAt: past }] },
+      { slug: 'auto-done', sections: [{ id: 'a', releasedAt: past }] }, // every lesson released => complete
+      { slug: 'soon', status: 'planned', sections: [] },
+    ],
+  }
+  assert.equal(isStudyDiscussionOpen('live'), true)
+  assert.equal(isStudyDiscussionOpen('done'), false)
+  assert.equal(isStudyDiscussionOpen('auto-done'), false)
+  assert.equal(isStudyDiscussionOpen('soon'), false)
+  assert.equal(isStudyDiscussionOpen('missing'), false)
+})